// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#pragma once

#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <isa_availability.h>
#include <random>
#include <string>
#include <vector>

inline void initialize_randomness(std::mt19937_64& gen) {
    constexpr std::size_t n = std::mt19937_64::state_size;
    constexpr std::size_t w = std::mt19937_64::word_size;
    static_assert(w % 32 == 0, "w should be evenly divisible by 32");
    constexpr std::size_t k = w / 32;

    std::vector<std::uint32_t> vec(n * k);

    std::random_device rd;
    std::generate(vec.begin(), vec.end(), std::ref(rd));

    std::printf("This is a randomized test.\n");
    std::printf("DO NOT IGNORE/RERUN ANY FAILURES.\n");
    std::printf("You must report them to the STL maintainers.\n\n");

    std::printf("Seed vector: ");
    for (const auto& e : vec) {
        std::printf("%u,", e);
    }
    std::printf("\n");

    std::seed_seq seq(vec.cbegin(), vec.cend());
    gen.seed(seq);
}

#if (defined(_M_IX86) || defined(_M_X64)) && !defined(_M_CEE_PURE)
extern "C" long __isa_enabled;

inline void disable_instructions(ISA_AVAILABILITY isa) {
    const unsigned long as_ulong = static_cast<unsigned long>(isa);

    auto has_env_var_escape_hatch = [] {
        size_t return_value = 0;
        char buffer[2]{};
        const errno_t err = ::getenv_s(&return_value, buffer, std::size(buffer), "STL_TEST_DOWNLEVEL_MACHINE");
        return err == 0 && buffer == std::string{"1"};
    };

    if (!has_env_var_escape_hatch()) {
        const bool has_feature = (__isa_enabled & (1UL << as_ulong)) != 0;
        if (!has_feature) {
            std::printf("The feature %lu is not available, the test does not have full coverage!\n"
                        "You can set the environment variable STL_TEST_DOWNLEVEL_MACHINE to 1,\n"
                        "if you intentionally test on a machine without all features available.\n",
                as_ulong);
        }
        assert(has_feature);
    }

    __isa_enabled &= ~(1UL << as_ulong);
}
#endif // (defined(_M_IX86) || defined(_M_X64)) && !defined(_M_CEE_PURE)

constexpr std::size_t dataCount = 1024;

template <class TestFunc>
void run_tests_with_different_isa_levels(TestFunc tests) {
    tests();

#if (defined(_M_IX86) || (defined(_M_X64) && !defined(_M_ARM64EC))) && !defined(_M_CEE_PURE)
    const auto original_isa = __isa_enabled;

    disable_instructions(__ISA_AVAILABLE_AVX2);
    tests();

    disable_instructions(__ISA_AVAILABLE_SSE42);
    tests();

    __isa_enabled = original_isa;
#endif // (defined(_M_IX86) || (defined(_M_X64) && !defined(_M_ARM64EC))) && !defined(_M_CEE_PURE)
}

template <class TestFunc>
void run_randomized_tests_with_different_isa_levels(TestFunc tests) {
    std::mt19937_64 gen;
    initialize_randomness(gen);

    run_tests_with_different_isa_levels([&] { tests(gen); });
}
